TWI447774B - Method for controlling wien filter for scanning electron microscope and scanning electron microscope having electron beam aligning function - Google Patents

Description

Control method for Wynn filter used in scanning electron microscope and scanning electron microscope with electron beam calibration function

The invention relates to a control method of a Wynn filter for a scanning electron microscope and a scanning electron microscope with an electron beam calibration function, and more particularly relates to a method for calibrating an electron beam to reach a place by using a Wynn filter. The desired target point is a scanning electron microscope using a control method of a Wynne mass filter and a scanning electron microscope having an electron beam calibration function.

Recently, it has not only been the minimization trend of information instruments, but also the field of cutting-edge materials is due to the industrialization of extremely fine technology, and it is required to provide information on the microstructure of fine structures or materials. In particular, since the second half of the 1990s, the world's research on nanotechnology has been active, and various studies have been carried out to identify the structure and properties of nanomaterials, and electron microscopy plays an important role in the axis.

In recent years, a scanning electron microscope has been widely used. The microscope scans the surface of a sample placed in a vacuum in a two-dimensional direction with a fine electron beam of about 1 to 100 nm, and detects the occurrence on the surface of the sample. The secondary electron signal displays an enlarged image on the screen or records the signal to analyze the fine structure of the sample form.

However, in the past, in order to calibrate the movement trajectory of the electron beam in order to enable the radiation electron beam to reach the desired target point, it is necessary to provide an additional positioning device.

Further, in the movement of the electron beam, the reliability of the sample is degraded due to the deformation of the cross-sectional shape.

Therefore, the object of the present invention is to solve such a conventional problem, and provide a control method for a Wynn filter for a scanning electron microscope and a scanning electron microscope having an electron beam calibration function, and the control method and the scanning electron microscope do not need to be provided with an additional The device, with the use of a Wynn filter, is capable of controlling the electron beam to reach a desired target point on the sample.

The stated object of the present invention is achieved by the following scheme. A control method for a scanning electron microscope using a Wynn filter, which is applied to a scanning electron microscope that allows electron beams emitted from a light source to pass through a sample of a Wynn filter to emit radioactive electrons through the The Wein mass filter is injected into the detector to detect the radioactivity, and the control method is characterized by comprising: a calculating step for calculating a final electric field and a final magnetic field to be applied to the Wynn filter The final electric field and the final magnetic field are used to cause an electron beam passing through the Wynn filter to reach a target point of the sample and to radiate from the sample and pass the Wynn filter The emitted electrons reach the detector; and an applying step of applying the final electric field and the final magnetic field to the Wynn filter.

In addition, the calculating step may include: an initial information acquiring step of acquiring an initial electric field and an initial magnetic field to be applied to the Wynn filter, the initial electric field and the initial magnetic field being used to pass the The electron beam of the mass filter moves vertically downward, and causes the radiation emitted from the sample and passing through the Wynn filter to reach the detector; and a calibration information acquisition step for obtaining the required A calibration electric field applied by the Wynn filter and a calibration magnetic field, the calibration electric field and the calibration magnetic field being used to cause the electron beam to reach a target point of the sample.

Furthermore, before the applying step, further comprising a correction information acquisition step for acquiring a correction electric field required by the Wynn filter, the correction electric field for correcting a cross-sectional shape of the electron beam, and The final electric field applied to the Wynn filter in the applying step includes the corrected electric field information.

Furthermore, the calibration information acquisition step may include a target point acquisition step of acquiring a position of the target point on the sample, and a ranging step of detecting a straight line from the Wynn filter to the target point The distance; and the final level force calculation step, calculating the final level of force required to be provided by the Wynn filter to the electron beam in order for the electron beam to reach the target point position.

In addition, the calibration information obtaining step may further include: a calibration information calculation step of calculating a calibration electric field and a calibration magnetic field required by the Wynn filter, the calibration electric field and the A calibration magnetic field is used to apply the final leveling force to the electron beam and to cause the emitted electrons passing through the Wayne mass filter to reach the detector.

Further, the electrostatic force applied to the electron beam by the calibration electric field and the magnetic force applied to the electron beam by the calibration magnetic field may be the same direction and the same size.

The object of the present invention is achieved by the following technical solutions. A scanning electron microscope having an electron beam calibration function for detecting radiation electrons emitted from the sample after an electron beam generated from a light source is incident on the sample, the scanning electron microscope having an electron beam calibration function is characterized by The method includes: a detector disposed between the electron beam and the sample for detecting the radiation electron; a Wein mass filter disposed under the detector to generate a magnetic field and an electric field to control the An electron beam and a movement trajectory of the radiation electron; and a control unit that controls an electric field and a magnetic field applied to the Wynn filter.

Furthermore, the control portion may include: a first calculating portion for calculating an initial electric field and an initial magnetic field to be applied to the Wynn filter, the initial electric field and the initial magnetic field being used to pass the The electron beam of the mass filter moves vertically downward; and a second calculating portion for calculating a calibration electric field and a calibration magnetic field to be applied to the Wynn filter, the calibration electric field and the calibration magnetic field are used to make The electron beam reaches a desired target point on the sample.

Furthermore, the control portion may further include a third calculating portion for calculating a correction electric field to be applied to the Wynn filter, the correction electric field for controlling an electron beam passing through the Wynn filter Profile shape.

According to the present invention, there is provided a control method for a Wynn filter for a scanning electron microscope, which can easily control the movement trajectory of an electron beam by using a Wynn filter.

In addition, the shape deformation of the electron beam can be easily corrected by using the Wynn filter.

Further, according to the present invention, there is provided a scanning electron microscope having an electron beam calibration function which can easily control the movement trajectory and shape of an electron beam by using a Wynn filter.

It is to be noted that, in the following various embodiments, structural elements having the same structure are collectively described in the first embodiment with the same reference numerals, and only the other embodiments are described. Different from the structure of the first embodiment.

Hereinafter, a control method of a Wynn filter for a scanning electron microscope according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Before describing the control method (S100) of the Wynn filter for scanning electron microscope according to the first embodiment of the present invention, a scanning electron microscope (100) having an electron beam calibration function used in the method of the present embodiment will be described and the application thereof will be described. Microscope detection method.

1 is a schematic view of a scanning electron microscope having an electron beam calibration function according to a first embodiment of the present invention.

Referring to FIG. 1, the scanning electron microscope (100) having an electron beam calibration function includes a lens barrel (110), a light source (120), a converging lens (130), an aperture (140), a detector (150), and a Wien filter. The plastometer (160), the objective lens (170), the sample holder (180), and the control unit (190).

The lens barrel (110) is for accommodating a light source (120), a condenser lens (130), a diaphragm (140), a detector (150), a Wynn filter (160), and an objective lens (170), which will be described later, in a housing In the inner exterior material, the end portion on the electron beam exit side, that is, the sample side end portion for arranging the sample is kept in a vacuum state.

The light source (120) is a member for scanning an electron beam generated by heating the cathode in the lens barrel (110) toward the side of the sample holder (180) on which the sample (S) is placed.

The converging lens (130) is a member for concentrating an electron beam emitted from the above-described light source (120) into one point.

The aperture (140) is a member for converting an electron beam concentrated by the converging lens (130) into a form having a certain wavelength.

The detector (150) is a member for detecting electrons emitted from the sample (S) after the injection of the electron beam, that is, radiation electrons including secondary electrons (Second Electro Electron), the detector (150) ) is disposed between the light source (120) and a Wean filter (160) to be described later.

On the other hand, in the process of moving from the sample (S) to the upper side, the emitted electrons are laterally offset by the Wynn filter (160) and injected into the detector (150), thus the detector (150) The front end face is preferably formed to be inclined so that the emitted electrons can be incident vertically.

2 is a schematic view of a Wynn filter in a scanning electron microscope having an electron beam calibration function shown in FIG. 1.

Referring to Figure 2, the Wean mass filter (160) is disposed between the detector (150) and the sample holder (180), i.e., the lower side of the detector (150), and the Wean mass filter (160) is controlled. The electron beam is caused to reach a desired target point by the movement trajectory of the lower electron beam, or the moving trajectory of the above-mentioned emitted electrons is controlled so that the emitted electrons are shifted toward the detector (150) side.

On the other hand, the Wean mass filter (160) has a structure in which a plurality of column electrodes (161) are mounted around an annular support member (162) surrounding a movement trajectory of electron beams or electrons, the column electrodes (161) includes: an electric field generating unit that generates an electric field by an applied voltage to apply an electrostatic force to the electron beam or the emitted electron; and a magnetic field generating unit that generates a magnetic field by the applied voltage to apply a magnetic force to the moving electron beam or the emitted electron .

On the other hand, in the present embodiment, the number of the column electrodes (161) is eight, but the number of the column electrodes (161) is not limited by the above number.

The control unit (190) is configured to control an electric field and a magnetic field generated by the Wynn filter (160), and includes an application unit (191), a first calculation unit (192), a second calculation unit (193), and a The third calculation unit (194).

The application unit (191) is connected to a first calculation unit (192), a second calculation unit (193), and a third calculation unit (194), which will be described later, and is used for each calculation unit (192, 193, 194). The final and calculated magnetic field information obtained and obtained is applied to the components of the Wynne mass filter (160).

The first calculating portion (192) is a component for calculating an initial electric field and an initial magnetic field information required by the Wynn filter (160), and the initial electric field and the initial magnetic field are used to generate the light source (120) from the upper side. The electron beam moves in the vertical direction without shifting, and shifts the movement trajectory of the emitted electrons emitted from the sample (S) on the lower side so that the emitted electrons are incident on the detector (150).

The second calculating unit (193) is a component for calculating the calibration electric field and the calibration magnetic field information required by the Wynn filter (160), and the calibration electric field and the calibration magnetic field are used without affecting the sample (S) In the state of the trajectory of the emitted radioactive electrons, the electron beams emitted by the light source (120) are concentrated to a desired target point on the sample.

That is, since the first calculating unit (192) calculates an electric field and a magnetic field required for the Wean mass filter (160) to shift the emitted electrons toward the detector (150) side, the second calculating unit (193) calculates The electron beam is calibrated to the desired target point and the calibration electric field and calibration magnetic field information required by the Wenneth filter (160).

The third calculating portion (194) is a component for calculating corrected electric field information required by the Wynn filter (160) for controlling the cross-sectional shape of the electron beam emitted by the light source (120).

That is, when the electron beam passes through the Wynn filter (160), the cross-sectional shape of the electron beam in the direction perpendicular to the moving direction is non-circular. If the cross-sectional shape of the electron beam is deformed, the pair cannot be ensured. The reliability of the detection result of the sample (S) is such that a correction electric field is additionally applied by the Wynn filter (160) to correct the shape of the electron beam.

Therefore, the third calculating portion (194) calculates the electric field information required by the Wynn filter (160) for correcting the shape of the electron beam and supplies it to the applying portion (191).

Next, the operation of the above scanning electron microscope having the electron beam calibration function will be briefly explained.

First, the electron beam scanned by the light source (120) passes through the converging lens (130) and the aperture (140) to reach the Wynne mass filter (160). At this time, the Wean mass filter (160) generates a final electric field and a final magnetic field by the control unit (190).

Through the electric field and magnetic field generated by the Wynn filter (160), the electron beam to which the electrostatic force and the magnetic force are applied passes through the objective lens (170) to reach the target point on the sample (S), and after the electron beam is injected, the test is performed. The sample (S) emits radioactivity including secondary electrons.

This radioactive electron moves upward and passes through the Wynne mass filter (160), while the radioactive electrons affected by the electrostatic and magnetic forces of the final electric field and the final magnetic field applied by the Wynn filter (160) are moved. It is biased toward the side of the detector (150) and is finally detected after it is injected into the detector (150).

On the other hand, a first embodiment of a method of controlling a Wynn filter in the above-described operation of a scanning electron microscope having an electron beam calibration function will be described in detail later.

3 is a flow chart showing a method of controlling a Wynn filter for a scanning electron microscope according to a first embodiment of the present invention.

Referring to Fig. 3, a control method (S100) of a Wynn filter for a scanning electron microscope according to a first embodiment of the present invention is a method of calibrating an electron beam using a Wynn filter (160), including a calculation step (S110) and The applying step (S120).

The calculating step (S110) is a step of calculating and obtaining the final electric field and final magnetic field information to be applied to the Wynn filter (160), including an initial information acquisition step (S111) and a calibration information acquisition step (S112).

Fig. 4 is a view for explaining an initial information acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

Referring to FIG. 4, the initial information acquisition step (S111) is a step of calculating and obtaining an initial electric field and initial magnetic field information required by the Wynn filter by the first calculation unit (192), the initial electric field and the The initial magnetic field is used to move the electron beam passing downward through the Wynn filter (160) vertically downwards in a state of no track offset, and to move the electrons of the electrons passing upward through the Wayne mass filter (160) The trajectory is shifted such that the emitted electrons move toward the detector (150) side.

In other words, it is assumed that the detected area in the sample (S) is located vertically below the Wayne mass filter (160), and this state is defined as the initial state. In this initial state, the electron beam is not required to cause a trajectory change due to the Wynn filter (160), but only the trajectory of the emitted electrons is required to be shifted toward the detector (150).

Accordingly, the first calculating unit (192) sets the initial magnetic field and the initial information, so that the electrostatic force applied to the electron beam (F _{M, 11)} and static electricity is applied to the radiation of electrons (F _{M, 12)} the same, and the applied The magnetic force (F _E,11 ) of the electron beam is opposite to the direction of the magnetic force (F _E,12 ) applied to the radioactive electrons but of the same magnitude.

The calibration information acquisition step (S112) is for calculating and obtaining a Wein filter for calibrating the electron beam through the second calculation portion (193) in the case where the injection target point of the electron beam is not vertically below ( 160) The step of calibrating the electric field and calibrating the magnetic field information, including a target point acquisition step (S113), a distance measurement step (S114), a final level force calculation step (S115), and a calibration information calculation step (S116).

Fig. 5 is a view for explaining a target point acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

Referring to Fig. 5, the target point acquisition step (S113) is a step of inputting a target point (T) on the sample (S) from the outside or specifying an arbitrary target point (T) internally to acquire a target point.

The ranging step (S114) is to sense or detect a linear distance from the position of the Wynn filter (160) applying electrostatic force and magnetic force to the electron beam to the target point (T) in the sample (S) Step (d).

The final level force calculating step (S115) is a linear distance (d) and an electron from the Wynn filter (160) to the target point (T) measured in the above-described ranging step (S114). The moving speed of the beam, etc., the step of calculating the force in the horizontal direction applied to the electron beam, that is, the final leveling force, in order to cause the electron beam to reach the target point (T).

Fig. 6 is a view for explaining a calculation procedure of calibration information in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

6 is explained as follows: the calibration information calculation step (S116) is a step for calculating a calibration electric field and a calibration magnetic field required by the Wynn filter (160), and the calibration electric field and the calibration magnetic field are used for not affecting the radiation. The final level force calculated in the above-described final level force calculating step (S115) is supplied to the electron beam in an electronic state.

That is, in this step, the calibration electric field and the calibration magnetic field are calculated such that the combination of the electrostatic force (F _{M, A1} ) and the magnetic force (F _{E, A1} ) applied to the electron beam passing through the Wynn filter (160) downward is The final level force is uniform and counteracts the electrostatic force (F _{M, A2} ) and the magnetic force (F _{E, A2} ) applied to the radiation electrons passing upward through the Wynn filter (160) without affecting the radioactivity.

Fig. 7 is a view for explaining an application step in a control method of a Wynn filter for a scanning electron microscope shown in Fig. 3.

Referring to Fig. 7, the following description is given: in the applying step (S120), the initial electric field and the initial magnetic field, the calibration electric field, and the calibration magnetic field obtained in the above calculating step (S110) are combined to calculate a final electric field and a final magnetic field, and these are used. The information control Wayne mass filter (160) produces a final electric field and a final magnetic field such that the electron beam passing through the Wynn filter (160) can reach the desired target point (T) on the sample (S), and The emitted electrons emitted from the sample (S) can be incident on the detector (150).

In other words, in this step, the applying unit (191) comprehensively calculates the initial electric field and the initial magnetic field information calculated and obtained by the first calculating unit (192) and the corrected electric field and the corrected magnetic field information obtained by the second calculating unit (193) to calculate The final electric field and the final magnetic field cause the final and electric fields to be generated by the Wynne mass filter.

Next, a control method (S200) for a Wynn filter for a scanning electron microscope according to a second embodiment of the present invention will be described.

Fig. 8 is a flow chart showing a method of controlling a Wynn filter for a scanning electron microscope according to a second embodiment of the present invention.

Referring to Fig. 8, a control method (S200) for a Wynn filter for a scanning electron microscope according to a second embodiment of the present invention is a method of calibrating an electron beam using a Wynn filter (160), including a calculation step (S110) and application. Step (S120).

The calculating step (S110) is a step for calculating and obtaining the final electric field and final magnetic field information to be applied to the Wynn filter (160), including an initial information acquisition step (S111), and a calibration information acquisition step (S112) And a correction information acquisition step (S117), wherein the initial information acquisition step (S111) and the calibration information acquisition step (S112) are the same as those in the first embodiment, and thus the repeated explanation is omitted.

Fig. 9 is a view for explaining a correction information acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 8.

Referring to Fig. 9, the correction information acquisition step (S217) is a step of calculating and obtaining a correction electric field required by the Wynn filter (160) through the third calculation portion (194) for making the passage through The abnormal shape of the electron beam of the Wean filter (160) is deformed to correct it to a normal shape.

That is, when an abnormal electron beam detecting sample (S) having a shape in which a cross section perpendicular to the moving direction of the electron beam is elliptical rather than circular is used, a problem that the detection reliability is lowered may occur, and thus the third calculating portion (194) Calculate the corrected electric field information required by the Wayne mass filter (160) in order to correct the shape of the electron beam. In other words, the third calculating unit (194) calculates a corrected electric field required by the Wean filter (160) in order to correct the shape of the electron beam by the electrostatic force (F _C ) applied to the electron beam.

Therefore, the calculated corrected electric field information is transmitted to the applying portion (191), and in the applying step (S120), the Wynn filter (160) is controlled to generate a final electric field in consideration of such corrected electric field information.

The present invention is not limited to the above-described embodiments and modifications, and can be embodied in various forms within the scope of the claims. It is to be understood that within the scope of the invention, the scope of the invention is intended to be within the scope of the invention.

100. . . scanning electron microscope

110. . . Lens barrel

120. . . light source

130. . . Converging lens

140. . . aperture

150. . . Detector

160. . . Wayne mass filter

161. . . Column electrode

162. . . Annular support member

170. . . Objective lens

180. . . Sample holder

190. . . Control department

191. . . Application department

192. . . First calculation department

193. . . Second calculation department

194. . . Third calculation department

F _M,11 . . . The electrostatic force initially applied to the electron beam

F _M,12 . . . Electrostatic force initially applied to radioactive electrons

F _E,11 . . . Magnetic force initially applied to the electron beam

F _E,12 . . . Magnetic force initially applied to radioactive electrons

F _{M, A1} . . . Electrostatic force applied to the electron beam passing through the Wynn filter

F _{M, A2} . . . Electrostatic force applied to the radiation electrons passing through the Wynn filter

F _{E, A1} . . . Magnetic force applied to the electron beam passing through the Wynn filter

F _{E, A2} . . . Magnetic force applied to the radiating electrons passing through the Wynn filter

F _C . . . Electrostatic force applied to an electron beam

S. . . Sample

T. . . Target

d. . . Straight line distance

1 is a schematic view of a scanning electron microscope having an electron beam calibration function according to a first embodiment of the present invention.

2 is a schematic view of a Wynn filter in a scanning electron microscope having an electron beam calibration function shown in FIG. 1.

3 is a flow chart showing a method of controlling a Wynn filter for a scanning electron microscope according to a first embodiment of the present invention.

Fig. 4 is a view for explaining an initial information acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

Fig. 5 is a view for explaining a target point acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

Fig. 6 is a view for explaining a calculation procedure of calibration information in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 3.

Fig. 7 is a view for explaining an application step in a control method of a Wynn filter for a scanning electron microscope shown in Fig. 3.

Fig. 8 is a flow chart showing a method of controlling a Wynn filter for a scanning electron microscope according to a second embodiment of the present invention.

Fig. 9 is a view for explaining a correction information acquisition step in the control method of the Wynn filter for the scanning electron microscope shown in Fig. 8.

100. . . scanning electron microscope

110. . . Lens barrel

120. . . light source

130. . . Converging lens

140. . . aperture

150. . . Detector

160. . . Wayne mass filter

170. . . Objective lens

180. . . Sample holder

190. . . Control department

191. . . Application department

192. . . First calculation department

193. . . Second calculation department

194. . . Third calculation department

S. . . Sample

Claims (7)

A control method for a scanning electron microscope using a Wynne mass filter is applied to a scanning electron microscope such that an electron beam generated from a light source passes through a Wynn filter and is emitted by a radioactive electron that passes through the sample. After the mass filter is injected into the detector to detect the emitted electrons, the control method is characterized by comprising: a calculating step for calculating a final electric field and a final magnetic field to be applied to the Wynn filter. The final electric field and the final magnetic field are used to cause an electron beam passing through the Wynn filter to reach a target point of the sample and to radiate from the sample and pass through the Wynn filter Radiating electrons reaching the detector; and applying step of applying the final electric field and the final magnetic field to the Wynn filter; wherein the calculating step comprises: an initial information acquisition step for obtaining a required An initial electric field applied by the Wynn filter and an initial magnetic field, the initial electric field and the initial magnetic field being used to move the electron beam passing through the Wynn filter vertically downward and The sample is radiated and passed through the electrons of the Wynn filter to the detector; and a calibration information acquisition step is performed for obtaining a calibration electric field and a calibration magnetic field to be applied to the Wynn filter. The calibration electric field and the calibration magnetic field are used to cause the electron beam to reach a target point on the sample. The method for controlling a Wynn filter for a scanning electron microscope according to claim 1, wherein the applying step further comprises a correction information acquiring step for acquiring the cross-sectional shape for correcting the electron beam. The corrected electric field required by the mass filter, the final electric field applied to the Wynn filter in the applying step includes the corrected electric field information. The method for controlling a Wynn filter for a scanning electron microscope according to the first aspect of the invention, wherein the calibration information acquisition step comprises: a target point acquisition step of acquiring a position of the target point on the sample; a step of detecting a linear distance from the Wynn filter to the target point; and a final level force calculation step calculating the need for the Wynn filter to bring the electron beam to the target point position The final level of force provided by the device to the electron beam. The method for controlling a Wynn filter for a scanning electron microscope according to claim 3, wherein the calibration information acquisition step further comprises a calibration information calculation step after the final level force calculation step, and calculating the Wean filter a calibration electric field and a calibration magnetic field required by the plastometer, the calibration electric field and the calibration magnetic field being used to apply the final level force to the electron beam, and to cause the radiation electrons to pass through the Wynn filter The detector. A method for controlling a Wynn filter for a scanning electron microscope according to claim 4, wherein the calibration electric field is applied to the The electrostatic force of the electron beam and the direction of the magnetic force applied to the electron beam by the calibration magnetic field are the same and the same size. A scanning electron microscope having an electron beam calibration function for detecting radiation electrons emitted from the sample after an electron beam generated from a light source is incident on the sample, the scanning electron microscope having an electron beam calibration function, characterized in that Included: a detector disposed between the electron beam and the sample for detecting the radioactivity; a Wein mass filter disposed under the detector to generate a magnetic field and an electric field to control the An electron beam and a movement trajectory of the electron emission; and a control unit that controls an electric field and a magnetic field applied to the Wynn filter; wherein the control unit includes: a first calculation unit configured to calculate a An initial electric field and an initial magnetic field of the Wynn filter, the initial electric field and the initial magnetic field are used to move an electron beam passing through the Wynn filter vertically downward; and a second calculating unit is used for calculation A calibration electric field to be applied to the Wynn filter and a calibration magnetic field for the electron beam to reach a desired target point on the sample. A scanning electron microscope having an electron beam calibration function according to claim 6, wherein the control portion further includes a third meter An arithmetic unit for calculating a corrected electric field to be applied to the Wynn filter, the corrected electric field for controlling a cross-sectional shape of an electron beam passing through the Wynn filter.